That said, it's rarely pays out. Quite the opposite: I often spending lots of time digging unnecessarily. I'm not complaining, I am who I am and I don't want to change. Digging into internals makes me happier and satisfied. And sometimes it is useful. So Linux kernel internals are on the roadmap and hopefully I'll dig into it some day.
I agree that absolute majority of people I met are not of that kind. And probably they should not. Learning business side of the software is what makes someone really useful. I hate business side, I only love computer side.